[23david]

Can you give some examples of TOML-based Rust package configurations that you think are good? My experience using TOML for config files has been very different.

IMO, using YAML for the config format is still the best option for most use-cases at this point. (Easy to support both json and YAML.) But I do think that it would be great to have a YAML successor that standardizes some of the cool things people are doing with custom YAML parses, and also removes outdated and unnecessarily complex parts of the original standard.